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2007 Silverado P0420 and P0430


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I have a 2007 Silverado 5.3 LT, Z71. I have had a check engine light on that had been on and was a P0420 code. I changed all the O2 sensors and reset.  It came back on it within 100 miles. I have dealt with it for awhile and I just checked the engine codes again and I have a P0420 and P0430 codes now. The truck seems to run fine and I did just change all coil packs. 

 

Any ideas? Screenshot_20181008-112330_Torque.thumb.jpg.c64a1aca6e4b769df9235f602121abb9.jpg

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5 minutes ago, Black02Silverado said:

Did you change the plugs along with the coil packs?  Just curious as to why you changed the coil packs as well?  Those never seem to go bad.  Is the truck using oil at all? 

Yes. Changed plugs.

It's using more oil than normal also. Like 3 to 4 quarts between changes. No visible leaks either.  PCV changed also

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28 minutes ago, skipcfd said:

Yes. Changed plugs.

It's using more oil than normal also. Like 3 to 4 quarts between changes. No visible leaks either.  PCV changed also

Using that much oil more than likely killed the CATS. 

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4 hours ago, Black02Silverado said:

Using that much oil more than likely killed the CATS. 

any idea where or how it could be burning the oil? I don't want to just replace the cats and then still have an oil problem

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43 minutes ago, skipcfd said:

any idea where or how it could be burning the oil? I don't want to just replace the cats and then still have an oil problem

If you have Active Fuel Management then that is one source.  The other can be from the intake.  My 2002 does not have AFM but was sucking oil from the intake area.  When I replaced the intake gasket and valley cover gasket. My oil consumption went to zero. 

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7 hours ago, Black02Silverado said:

If you have Active Fuel Management then that is one source.  The other can be from the intake.  My 2002 does not have AFM but was sucking oil from the intake area.  When I replaced the intake gasket and valley cover gasket. My oil consumption went to zero. 

I do have active fuel management... but what do I do to fix it?

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